Patent GB-616474-A (GB)
Title: Improvements relating to variable speed gears
IPC: F16H3/091
Filed: 1946-09-05
Abstract: 616,474. Controlling change-speed gearing. NAYLOR, J. T., and ATKINSON LORRIES (1933), Ltd. Sept. 5, 1946, No. 26717. [Class 80 (ii)] In. countershaft change-speed gearing of the kind having alternative constant-mesh gear pairs both between the input and lay-shafts and between the lay and output shafts, the operative gear train between the input and layshafts is selected by a clutch member slidable on the lay-shaft whilst of the gear trains between the lay and output shafts one has a gear on the lay and one a gear on the output shaft slidable to engage respectively therewith, the gear meshing the slidable gear on the lay-shaft being adapted to engage the input shaft for direct drive. As shown, applied to a five-speed and reversing gear, a short input shaft 1, Fig. 3, supported at both ends in bearings in the gear casing and having an internally splined end projecting through the casing wall for engagement with the dogged end of an external driving shaft 4, carries integrally gears 13, 16 in constant mesh with gears 14, 17 freely rotatable on a lay-shaft 3 and alternatively clutchable thereto by a double dog clutch member 18 slidably splined on the lay-shaft. An output shaft 2 journalled at its inner end in the input shaft 1 has splined thereon a gear 20 slidable to bring its splines also into engagement with splines 1a on the adjacent end of the input shaft for direct drive. The gear 20 meshes constantly a gear 21 freely mounted on the lay-shaft 3 and slidable to effect a clutch connection 21a, 22 therewith. A further gear 23 freely mounted on the output shaft 2 but slidable to the left thereon into splined engagement therewith meshes constantly a gear 24 integral with the lay-shaft 3. A reversing idler 25, shown rolled into the plane of the drawing, meshes constantly a gear 22 integral with the lay-shaft 3 and may be engaged also by the gear 20 on sliding the latter to the right. The idler 25 is journalled on a stub-shaft 25a withdrawable endwise through the gear casing to allow removal of the idler through a casing opening normally closed by a cover-plate 25d, which, however, may be replaced by a casing 30 mounting a power takeoff shaft 33 having a gear 36 slidable to mesh the idler 25. The gear changes are controlled by a " gate " or " ball " lever movable to engage gaps 29, Fig. 4, in three slidable selector rods 26 ... 28 actuating the clutch member 18, the sliding gears 21, 23 and the sliding gear 20 respectively. With the rods and gearing members in the position shown, the transmission is in neutral, all the clutch connections being disengaged. For first and second speeds, the change lever is engaged with the rod 26 and moves it to the right to engage the gear train 13, 14, the change lever then passing into the right-hand gap in the rod 27 and moving it to the left or right to entrain the gear 23 or gear 21 respectively. For third and fourth speeds, the change lever is again engaged with the rod 26 and moves it to the left to engage the gear train 16, 17, the lever then passing into the left-hand gap in the rod 27 and moving it to the left or right as before. Direct drive is engaged by passing the change lever into the right-hand gap in the rod 28 and moving the latter to the left to entrain the shaft 1 with the gear 20, the lay-shaft idling through the gear pair 16, 17. Reverse is engaged, using the gear pair 16, 17, by passing the change lever into the left-hand gap in the rod 28 and moving it to the right to entrain the gears 20, 25. The gear pair 13, 14 may be similarly employed to give a second reverse ratio. The lay-shaft 3 has axial adjustment means at both ends. The shaft bearings in the external gear casing may employ rollers instead of the balls shown. In Fig. 1 (not shown) of the drawings accompanying the Provisional Specification, the positions of the gear pairs 13, 14 and 16, 17 are interchanged, giving a slightly modified gear selection, and the lay-shaft is axially adjustable from the forward end only, a roller bearing being substituted for the rear ball bearing. According to the Provisional Specification, the clutch 18 may be on the input shaft and additional gear trains may be incorporated between the lay and output shafts. In any of the gearings described the output shaft may be used as the input shaft and vice versa.